Frost Dates for 66027 — Fort Leavenworth, Kansas

Half of springs at Leavenworth, KS see their last 32°F night by April 12; only one in ten is past it by March 31, and one in ten still has one after April 25. Planting tender crops after April 17 leaves a 30% risk of a frost on them, after April 21 20%, and after April 25 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 65% of the 110 Kansas stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 27 in half of years, as early as October 13 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 8 days later, around November 4; in spring the one-in-ten date for 28°F is April 17, 8 days before the 32°F one. The freeze-free season lasts 196 days in a typical year, longer than at 74% of the 110 Kansas stations; it reaches 216 days one year in ten and falls short of 176 one year in ten. On average 105 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 9 days longer, to about April 21, and return around October 18. Severe cold of 16°F or below comes every winter, usually between December 1 and March 5.

July is the warmest month at Leavenworth, KS, averaging 91°F by day and 69°F at night; January is the coldest at 39°F and 21°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 87% of years.

Warmth for growing adds up to 4,281 growing degree days a year (base 50°F), more than at 72% of the 110 Kansas stations. 37% of them (1,572) have built up by the end of June, and July adds the most, 925. Precipitation totals 41.4 inches a year, most in June (5.5") and least in January (1.1"); May to September bring 60% of it.

The nearest other station, Leavenworth 3SW, KS, 4 miles south of Fort Leavenworth, has a last frost 7 days later (April 19), a first frost 8 days earlier (October 19), a season 15 days shorter.

The first measurable snow (0.1 inch or more) in Fort Leavenworth usually arrives around November 30, and the last of the season around March 9. Those are the middle dates across the winters of 1991–2020 at Leavenworth, KS, 1.7 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 34 days after the last snow.

ZIP 66027 is 2 miles from Leavenworth, KS, which stands at 870 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 66027 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.